public class Day_17_2_二叉树的镜像 {
    public class TreeNode {
        int val = 0;
        TreeNode left = null;
        TreeNode right = null;

        public TreeNode(int val) {
            this.val = val;

        }
        public void Mirror(TreeNode root) {
            if (root == null || (root.left == null && root.right == null)) {
                return;
            }
            TreeNode temp = new TreeNode(-1);
            temp = root.left;
            root.left = root.right;
            root.right = temp;

            if (root.left != null) {
                Mirror(root.left);
            }
            if (root.right != null) {
                Mirror(root.right);
            }
        }
    }
}
